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microwaves

Since I’m putting together a 10Ghz Transverter, the question of TX/RX Switching and sequencing comes to mind when gathering all the components for the build. For sequencing, I had a good look around at what was available from various sources on the web, but always came back to the Minikits product.

It seems to tick all the boxes as to what I needed it to do, so I ordered the kit from Mark. It turned up a quick 2 days after the funds cleared, and I wasted no time in constructing and testing it with the little Yaesu FT817 rig I use for microwave IF.

The Minikits EME166 kit is supplied with a beautifully made double sided, solder masked and silk screened PCB measuring 94 x 55 mm. It features 4 sequenced outputs, works on a supply voltage of between 8 to 15Vdc. It will handle up to 4 watts of RF from the IF radio between 28 and 500Mhz. It can be switched by RF sensing, or from a 12 volt or 0 volt signal via the IF radio’s coax centre conductor. It can also be manually switched if that is required. This kit comes with all the parts you need, besides the IF RF connectors, so you can make up your own mind as to how you’ll roll.

There is some surface mount soldering involved, but if you’re “messing about with Microwaves” your probably quite used to hunching over a magnifier lamp and soldering tiny components by now!

I have it down to a fine art these days, fluxing the area to be soldered with a flux pen, nice new, fine, clean tip and doing everything in a small plastic tray (Fererro Rocher plastic chocolate container lids work well!) that fits the board I’m soldering to. I empty the tiny components into the tray and pick them up with tweezers and solder them onto the board in the tray – this very much reduces the risk of losing the tiny flea sized components. There is nothing worse than trying to find an 805 sized component on the floor or in the shag pile carpet! ( …even worse when you have no spares)

Besides the few smd parts that are fitted to the underside of the board, there are 4 smd diodes fitted to the top of the board. The rest of the conventional leaded components go on easily. I built the kit in around 4 hours. I’d class this kit as “intermediate” level, you’ll need some SMD soldering gear and some experience to successfully build the kit. Don’t forget to check the values of the resistors with your multimeter, it’s easy to make a mistake!

One of the good things about this upgraded version, ( it’s an update of the very popular EME66 sequencer kit that has found its way into many a Transverter project worldwide over the years) is the single in line connector for all the sequenced outputs. This makes it much easier and neater to wire the board into your project. It’s also over voltage an reverse polarity protected.

I elected to fit SMA connectors to the board. The only thing I’d like to see different in the next version is the facility to mount the connectors vertically on the board, so it will be much easier to work with a vertically mounted sequencer.

My RX/TX change over Relay is 26 Volts, and the kit allows you to easily integrate different voltages to be switched by omitting the required link and soldering the supply to be switched at this point. Here you can see where I have the 26v supply (yellow wire) coming in to TX2 where the link for the 12v supply would normally be. It’s versatile, flexible and simple. It’s probably a good idea to change the corresponding led resistor to a more suitable value than the 1K0 supplied for 12 v.

The RX and TX IF levels are adjustable via the trim pots. Installing Link 5 will switch in a delay back to RX when using SSB to stop the relay chattering. I found the delay a bit long when using RF switching for my tastes. This could possibly be shortened by changing the associated cap value, if required.

Finally, here is a short video of the sequencer in operation. I’m using my FT817 that has been modified to put 12 Volts on the centre conductor of the front panel BNC connector when the PTT is enabled. The switching delay trim pot adjustment on the EME166 is about set mid-way.

Conclusion: The Minikits EME166 Transverter kit comes highly recommended. The design is very versatile, flexible and uses super quality parts through out. Delivery was prompt and Mark was very easy and pleasant to deal with.